As is known, a printing press of the above type essentially comprises a drum of considerable diameter around which the sheet material for printing is conveyed, said sheet material being unwound from an unwinding roll and rewound, after printing, onto a winding roll.
Depending upon the pattern to be printed on the sheet material, that is according to the number of colours to be transferred onto it, a plurality of inking units is disposed along the periphery of said drum, each comprising an inking or anilox roller, which picks up the ink from a special tank by means of special cuts or cells in its skirt and transfers it to a printing cylinder proper, or plate cylinder, which carries out printing on the sheet material.
In such a printing press the inking traits, or at least the print cylinders, must be replaced each time the pattern to be printed changes.
The cylinder replacement operation is rather long and laborious since these are normally supported between the two sides of the machine.
Complete removal of such cylinders thus entails releasing their ends from the sides of the machine and using hoists to handle them.
In order to avoid complete replacement of the cylinders, which is also very costly, systems have recently been proposed that provide for removal only of the outer liner of the cylinders.
A known arrangement consists of swinging the support of one end of the cylinder outwards and raising the cylinder axle, in order to have enongh room to slip off the liner. According to this method only the print cylinder, and not the inking or anilox cylinder, is normally removed.
Another method known to the art consists in sliding the cylinder supports upward along the sides of the press, so that their liners can then be slipped off horizontally.
This method holds the drawback of having to work in a somewhat limited space to slip off the cylinder liners, and having to work on one cylinder assembly at a time. Moreover, making the cylinder supports mobile weakens the press structure.
The aim of the invention is to overcome the above drawbacks, providing a device that allows easy and rapid replacement of the inking unit cylinder liners, with ample space for access to them.
Another aim of the invention is to provide a device of this type that leaves the sturdiness of the press virtually unaltered.
These aims are achieved by the press according to the invention which has the characteristics listed in the attached claim 1.
Preferred embodiments of the invention are disclosed in the dependent claims.
Essentially, at least a mobile shoulder is provided on at least one of the two sides of the press supporting the counter drum and the inking units, it being possible to move said shoulder from a closed position in which it supports the inking cylinders to an open position in which it simultaneously releases all the inking cylinders associated with it. Suitable mechanisms are provided to release the supported ends of the inking unit cylinders, in order to prevent them from interfering with the movement of the mobile shoulder during opening and closing.